textproduct: Quad Cities

KEY MESSAGES

- Level 2/3 out of 5 risk for severe weather this evening/tonight for damaging winds (some significant?) and possibly brief spin-up tornado, as an organized complex of storms propagate into the area.

- Warm and increasingly humid conditions will fuel periodic storms Saturday night into Tuesday. Severe storms are possible, and the coverage could be spotty before becoming more widespread late Sunday and Monday.

SHORT TERM /THROUGH TONIGHT/

Issued at 240 AM CDT Fri May 15 2026 Ongoing elevated convection mainly across our southern counties should weaken and shift out of the area by 12z, with the weakening and veering of the nocturnal LLJ and passage of a mid level shortwave. In the wake, the main story for today will be a dry and warm day and occasionally breezy beneath increasing solar insolation. Highs should range from near 80 east to the mid 80s west where a few upper 80s are also possible. Humidity will also begin to nudge upward, especially across southern areas where dew points are likely to be in the 60s.

The focus later today for storms looks to be well to our west along a stalled boundary extending from KS through nw IA and MN. A more concentrated corridor of initiation is being suggested across parts of sw MN/nw IA into e NE attendant to a mid level shortwave and the entrance region of an upper jet streak. Strong instability and a ramping LLJ should promote eventual upscale growth into one or two MCS's, which will look to track e/se and into the region as the evening progresses. This convection should be in the process of going from the mature phase to a gradual weakening phase as it moves across by mid/late evening into the early overnight. The main threat will be damaging winds with potentially some gusts 70+ mph possible particularly north/west of the Quad Cities where the greater potential for mature/ organized convection exists and is highlighted by an Enhanced Risk (Level 3 out of 5) from SPC. DCAPE values are progged around 1000 j/kg with robust deep layer shear easily supportive of the damaging wind threat. In addition, brief tornadoes can't be totally ruled out with 0-3km shear vectors around 30kt from the SW. Some uncertainty to the damaging wind threat will then exist heading further east to the Miss. River and into nw IL due to a potential near surface stable layer.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 240 AM CDT Fri May 15 2026

Saturday should be a day of increasing solar insolation fostering a rebound in highs into the 80s, with another nudge up in the humidity levels with widespread dew points in the 60s. Forcing is rather nebulous with some weak height rises depicted at 500 hPa. But, there is potential by mid to late PM with strong surface heating to weaken any CIN and trigger widely scattered storms. Low level shear is quite weak, but 30-40 kt of 0-6km shear and fat CAPE profiles would support a risk for severe storms perhaps with some supercellular characteristics capable of large hail and damaging winds. Coverage would appear to be spotty, and storms could continue beyond sunset. Blended guidance is quite high with precipitation chances evolving Saturday night into Sunday AM along/north of I-80 likely attendant to increasing WAA ahead of a lifting warm front as an upper trough undergoes amplification across the western CONUS. Seemingly the signal for the main LLJ core and advection appear to be aimed further west, and so my confidence on these higher PoPs is low. Nonetheless, we'll have a chance for showers and storms Saturday night into Sunday morning with the warm front lifting through the region. Thereafter, much of Sunday will be very summery as we are placed firmly within the warm sector with highs well into the 80s to possibly near 90 in a few spots and humid conditions. This could again trigger some widely scattered late day convection of which could be severe due to the abundant instability and at least modest shear.

The details in the forecast become murky late in the weekend through early next week, and severe storm potential will likely hinge some on previous days convective trends/evolution. That said, synoptically with the upper trough slowly shifting east placing the region in strengthening SW flow aloft shuttling embedded disturbances, and a surface cold front inching closer we have perhaps our best potential for more widespread storms and increased coverage of strong/severe storms late in the weekend through early next week. Potential to see another organized convective complex work through the area Sunday evening/night, and then how this evolves could play into the timing/location/threat for severe weather on Monday.

It looks like the cold front will shift through the region on Tuesday with one last chance for storms. Uncertainty still abounds with regards to any severe threat Tuesday, which is largely dependent upon the frontal timing. Cooler and more seasonable conditions look to settle in mid next week.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1210 AM CDT Fri May 15 2026

Impacts:

- Showers and storms 07z-11z mainly south including BRL - Sporadic southerly wind gusts to 20 kt - Round of gusty showers/storms possibly arriving later Friday evening.

Discussion:

One area of showers and isolated storms has pushed east of DBQ and MLI terminals. Much of the short term CAM guidance is in good agreement on redevelopment of more showers and some storms 07z-11z, mainly south of I-80 and especially along and south of U.S. Hwy 34. Have maintained PROB30 mention for a shower at MLI during this timeframe, and kept a prevailing shower mention at BRL with a PROB30 for thunder. After the precipitation ends some lower ceilings, predominantly VFR at 3500-5000ft agl, are possible into mid morning Friday with a low chance (20%) for MVFR near BRL and MLI. Southerly winds look to remain around 10 kt into Friday and gusty occasionally to around 20 kt. Another round of showers and storms is anticipated to move into portions of the area Friday evening, with the better coverage suggested west of the Mississippi River prior to 06z/16. Have gone with PROB30 mention for thunder at CID and DBQ after 02z/16 for now. It's possible that convection can get into MLI and BRL prior to the end of the TAF period, but just not confident enough to include mention at this time. Will certainly refine the precipitation mention as we get closer. Gusty winds 40-50+ kt could also accompany the convection Friday evening.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.